<template>
  <div>
    <h1>当前求和为：{{sum}}</h1>
    <select v-model.number="selectedNumber">
      <option value="1">1</option>
      <option value="2">2</option>
      <option value="3">3</option>
      <option value="4">4</option>
    </select>
    <button @click="increment">+</button>
    <button @click="decrement">-</button>
    <button @click="incrementOdd">当前求和为奇数再加</button>
    <button @click="incrementWait">等一等再加</button>
  </div>
</template>

<script>
export default {
  name: 'count',
  data () {
    return {
      sum: 0,
      selectedNumber: 1
    }
  },
  methods: {
    increment () {
      this.sum += this.selectedNumber
    },
    decrement () {
      this.sum = this.selectedNumber
    },
    incrementOdd () {
      if (this.sum % 2) {
        this.sum += this.selectedNumber
      }
    },
    incrementWait () {
      setTimeout(() => {
        this.sum += this.selectedNumber
      }, 1000)
    },
  },
}
</script>

<style lang="css" >
button {
  margin-left: 5px;
}
</style>